The frontrunner in the Conservative leadership race has promised that if he becomes Prime Minister he will cut taxes for around three million high earners by raising the threshold of the top 40p rate of income tax from £50,000 to £80,000.
The policy will hand £9.6bn to the highest earning households.
However, new figures obtained by Leeds West MP Ms Reeves show that nearly half – 44 per cent – of those who would benefit live in London (23 per cent) and the South East (21 per cent).
According to the figures, compiled by the House of Commons library, just 6 per cent of the beneficiaries would be higher rate taxpayers in Yorkshire and the Humber.
The findings also show that of the total of UK taxpayers (excluding Scotland), only 3 per cent of higher rate taxpayers to benefit live in the North East and just 9 per cent live in the North West.
Ms Reeves said: “These figures show that Boris Johnson’s income tax giveaway is nothing more than a cynical bribe aimed at securing him votes for the Tory leadership to get him into Downing Street.
“His ill-judged plan would overwhelmingly benefit higher rate taxpayers in London and the South East at the expense of overstretched hospitals, schools and transport systems in the North which continue to be starved of investment.
“It would be entirely unjust to give away almost £10bn to better off households at a time when we need to be spending more on the NHS, social care and other vital public services in Yorkshire and across the country.
The Labour MP added: “Boris has form when it comes to fantasy figures with his claim during the EU referendum that voting Leave would mean an extra £350m a week for the NHS.
“His latest financial pledge on tax is just evidence of muddled-headed economics from a man who can’t be trusted.”
Announcing his plans in his weekly Telegraph column last week, Mr Johnson wrote: “We should be cutting corporation tax and other business taxes.
“We should be raising thresholds of income tax – so that we help the huge numbers that have been captured in the higher rate by fiscal drag.
He added: “We can go for much greater economic growth – and still be the cleanest, greenest society on earth.”